C/1986 P1-A Wilson
more info
Comet C/1986 P1-A was discovered on 5 August 1986 by Christine Wilson (Mount Palomar, California, USA), that is 8.5 months before its perihelion passage. This comet was last observed in mid-April 1989. Splitting event observed in comet Wilson was occured after perihelion passage.
Comet had its closest approach to the Earth on 1 May 1987 (0.623 au), less than two weeks after perihelion passage. According to Minor Planet Center, the main component A of this comet exhibits nongravitational acceleration in the time interval 5 August 1986 – 11 April 1989. Therefore, the non-gravitational orbit from the whole observational arc (spanning over 2.68 yr in a range of heliocentric distances: 3.64 au – 1.200 au (perihelion) – 7.83 au.) are given here as preferred orbit.

This Oort spike comet suffers large planetary perturbations during its passage through the planetary system; these perturbations lead to a more tight future orbit with semimajor axis of about 1,300 au.
See also Królikowska and Dybczyński 2010, Królikowska 2014 and Królikowska 2020.

solution description
number of observations 687
data interval 1986 08 05 – 1989 04 11
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 3.64 au – 1.20 au (perihelion) – 7.83 au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting YES
number of residuals 1361
RMS [arcseconds] 1.11
orbit quality class 1a
orbital elements (heliocentric ecliptic J2000)
Epoch 1987 05 05
perihelion date 1987 04 20.78069282 ± 0.00005371
perihelion distance [au] 1.19965105 ± 0.00000087
eccentricity 1.00031319 ± 0.00000315
argument of perihelion [°] 238.307145 ± 0.000054
ascending node [°] 111.666056 ± 0.000041
inclination [°] 147.119122 ± 0.000029
recip semi-major axis [10-6 au-1] -261.07 ± 2.63
Time distribution of positional observations with corresponding heliocentric (red curve) and geocentric (green curve) distance at which they were taken. The horizontal dotted line shows the perihelion distance for a given comet whereas vertical dotted line – the moment of perihelion passage
non-gravitational parameters
A1 [10-8au\day-2] 1.7501 ± 0.06
A2 [10-8au\day-2] 0.003349 ± 0.027144
A3 [10-8au\day-2] 0 (assumed)
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113